1. Field of the Invention
This invention relates to improvements in large off-highway vehicles and more particularly, but not by way of limitation, to a rear dump tilting body two axle type large off-highway vehicle.
2. Description of the Prior Art
Off-highway vehicles are in widespread use today for hauling extremely large and heavy loads in order to reduce time and expense in many industries, such as in the open mining industry, large construction industry, and the like. These hauling vehicles are usual dump-type vehicles, with some of the vehicles having a bottom dump feature, as shown in the Goodbary Pat. No. 4,106,813, issued Aug. 15, 1978 and entitled "Bottom Dump Door Linkage Apparatus and Dump Body Partition Means". Other off-highway dump vehicles are of the conventional tractor-trailer hauling unit such as shown in the Lackey et al U.S. Pat. No. 3,134,628, issued May 26, 1964 and entitled "Tilting Dumping Trailer." These rear dump tilting body units are usually powered only on the middle axle and if proper tire loading is maintained for a balanced design, there is usually not adequate loading on the drive axle for negotiating roadway grades. As a result, tractor-trailer units of this type are normally limited to use wherein road grades of not more than three percent or four percent, maximum, are present. In addition, tractor-trailer type off-highway hauling equipment usually has only three points of support and as a result may turn over somewhat readily. The relatively high center of gravity of these units also increases the instability thereof. Some activity has taken place in the development of self-contained tilting body rear dump vehicles, as opposed to the tractor-trailer type, such as that shown in the Kelley Pat. No. 3,786,889, issued Jan. 22, 1974, and entitled "Steerable Load Transporting Vehicle."
Under actual operating conditions these self-contained rear dump vehicles have certain disadvantages which particularly become apparent as the loading handling weight requirements have increased. For example, it is now desirable to provide vehicles of this type which will carry weights of 200 to 235 tons, and these operational conditions have produced working strains and problems in the use of the presently available vehicle equipment. For example, main frame design has been found to be lacking in sufficient strength for such working or operating conditions, the suspension mounting arrangements also are found to be insufficient and result in short useful life expectancy for the equipment. The safety and efficiency of the vehicle braking system also falls short of acceptable performance, particularly in the hand brake system on these large off-highway vehicles; the dump body design in and of itself frequently is not of a construction for receiving the required quantity of material under these large volume and weight hauling conditions; the cooling system for the radiator and fan assembly is frequently inadequate; as well as overall operator safety and comfort for the operator of the equipment is frequently less than desirable.